# Sex specific effects of adoptive Tregs transfer on the brain and periphery in maternal immune activation offspring rescuing immune dysregulation

## TL;DR

This study shows that transferring regulatory T cells can reduce inflammation and improve behaviors in male and female offspring of mothers with immune activation, but the effects differ by sex.

## Contribution

The study reveals sex-specific effects of Treg transfer on immune and behavioral outcomes in a maternal immune activation model.

## Key findings

- Treg transfer reduced TH17 cells and inflammatory cytokines in male MIA offspring.
- Female MIA offspring showed increased cytokine production after Treg transfer.
- Treg-treated male MIA offspring exhibited gene expression changes linked to neurodevelopmental functions.

## Abstract

Autism spectrum disorder (ASD) is characterized by atypical communication, social interactions, and restricted interests. In ASD, there are dysfunctional immune regulatory control mechanisms that can lead to immune activation. Notably lower frequencies of regulatory T cells (Tregs) and reduced immunosuppressive cytokines are reported and associated with more impaired behaviors impacting both individuals with autism and their families. Therefore, therapeutic approaches that enhance immune regulation may offer substantial benefits. Using the maternal immune activation (MIA) model, we investigated whether adoptive transfer of wildtype Tregs into MIA offspring recipients could rescue immune activation, brain transcriptome changes and behaviors exhibited in adult MIA offspring. We also aimed to explore potential sex-differences in responses. In male but not female MIA offspring, Tregs transfer reduced the frequency of T helper (TH)-17 (RORγT+ CD4+) T cells in both the mesenteric lymph node (MLN) and spleen. Moreover, the frequency of CD25+Foxp3+ T cells was increased in the MLN and spleen of male but not female MIA offspring following Treg transfer. Splenocytes from male MIA offspring receiving Tregs showed reduced production of inflammatory cytokines (e.g., IL-6 and TNFα) following PMA/Ionomycin stimulations. In contrast, female MIA offspring that received Tregs exhibited different cytokine profiles characterized by increased production of cytokines, including GM-CSF, IFNγ, and IL-10. In the brain, bulk mRNA sequencing in the cerebellum, frontal cortex, and hippocampus revealed that Tregs-treated male MIA offspring had differentially expressed genes involved in neurodevelopmental disorders, synaptic function, and epigenetic regulation. Minimal gene expression differences were observed in female counterparts. There was significant improvement in self-grooming behaviors in males MIA offspring that received Tregs. In females, social novelty improved after Tregs treatment. In summary, adoptive Tregs transfer reduced systemic inflammation, brain transcription and behavior alterations in a sex dependent manner in the context of MIA. These findings suggest that adoptive Treg transfer may represent a viable therapeutic avenue for mitigating systemic inflammation and comorbidities associated with MIA and neurodevelopmental disorders such as ASD.